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PHP implements file upload to server (including code)

烟雨青岚

Release： 2023-04-08 22:08:01

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PHP implements file upload to server (including code)

php implements file upload to the server (including code)

Create a file upload form

Allowing users to upload files from a form is very useful.

Please look at the following HTML form for uploading files:

<html>
<body>
<form action="upload_file.php" method="post"
enctype="multipart/form-data">
<label for="file">Filename:</label>
<input type="file" name="file" id="file" /> 
<br />
<input type="submit" name="submit" value="Submit" />
</form>
</body>
</html>

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Please note the following information about this form:

tag The enctype attribute specifies which content type to use when submitting the form. Use "multipart/form-data" when your form requires binary data, such as file content.

The type="file" attribute of the tag specifies that the input should be processed as a file. For example, when previewing in a browser, you'll see a browse button next to the input box.

Comment: Allowing users to upload files is a huge security risk. Please allow only trusted users to perform file upload operations.

Create upload script

The "upload_file.php" file contains the code for uploading files:

<?php
if ($_FILES["file"]["error"] > 0)
  {
  echo "Error: " . $_FILES["file"]["error"] . "<br />";
  }
else
  {
  echo "Upload: " . $_FILES["file"]["name"] . "<br />";
  echo "Type: " . $_FILES["file"]["type"] . "<br />";
  echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";
  echo "Stored in: " . $_FILES["file"]["tmp_name"];
  }
?>

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By using PHP's global array $_FILES, You can upload files from a client computer to a remote server.

The first parameter is the input name of the form, and the second subscript can be "name", "type", "size", "tmp_name" or "error". Like this:

$_FILES["file"]["name"] - The name of the uploaded file $_FILES["file"]["type"] - The type of the uploaded file $_FILES[" file"]["size"] - The size of the uploaded file, in bytes $_FILES["file"]["tmp_name"] - The name of the temporary copy of the file stored on the server $_FILES["file"][ "error"] - Error code caused by file upload

This is a very simple way to upload files. For security reasons, you should add restrictions on who has permission to upload files.

Upload restrictions

In this script, we have added restrictions on file uploads. Users can only upload .gif or .jpeg files, and the file size must be less than 20 kb:

<?php
if ((($_FILES["file"]["type"] == "image/gif")
|| ($_FILES["file"]["type"] == "image/jpeg")
|| ($_FILES["file"]["type"] == "image/pjpeg"))
&& ($_FILES["file"]["size"] < 20000))
  {
  if ($_FILES["file"]["error"] > 0)
    {
    echo "Error: " . $_FILES["file"]["error"] . "<br />";
    }
  else
    {
    echo "Upload: " . $_FILES["file"]["name"] . "<br />";
    echo "Type: " . $_FILES["file"]["type"] . "<br />";
    echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";
    echo "Stored in: " . $_FILES["file"]["tmp_name"];
    }
  }
else
  {
  echo "Invalid file";
  }
?>

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Save the uploaded file

The above example is in the server's PHP temporary The folder creates a temporary copy of the uploaded file.

This temporary copied file will disappear when the script ends. To save the uploaded file, we need to copy it to another location:

<?php
if ((($_FILES["file"]["type"] == "image/gif")
|| ($_FILES["file"]["type"] == "image/jpeg")
|| ($_FILES["file"]["type"] == "image/pjpeg"))
&& ($_FILES["file"]["size"] < 20000))
  {
  if ($_FILES["file"]["error"] > 0)
    {
    echo "Return Code: " . $_FILES["file"]["error"] . "<br />";
    }
  else
    {
    echo "Upload: " . $_FILES["file"]["name"] . "<br />";
    echo "Type: " . $_FILES["file"]["type"] . "<br />";
    echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";
    echo "Temp file: " . $_FILES["file"]["tmp_name"] . "<br />";
    if (file_exists("upload/" . $_FILES["file"]["name"]))
      {
      echo $_FILES["file"]["name"] . " already exists. ";
      }
    else
      {
      move_uploaded_file($_FILES["file"]["tmp_name"],
      "upload/" . $_FILES["file"]["name"]);
      echo "Stored in: " . "upload/" . $_FILES["file"]["name"];
      }
    }
  }
else
  {
  echo "Invalid file";
  }
?>

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The above script detects whether the file already exists. If it does not exist, it copies the file to the specified folder.

Note: This example saves the file to a new folder named "upload".

Start taking out the third element of the array and return the remaining elements in the array:

<?php
$a=array("red","green","blue","yellow","brown");
print_r(array_slice($a,2));
?>

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Thank you for reading, I hope you will benefit a lot.

Original link: https://www.cnblogs.com/yszr/p/10522067.html